A locking device/mechanism for a baby car seat in the prior arts, such as the one in the Chinese utility model patent CN201472193U, comprises: a base whose front end is provided with a locking groove and whose inside is provided with a cavity; and a locking hook provided in the cavity and rotatably connected to the base via a rotating shaft, a front part of the locking hook including a hooking groove with an downward opening, wherein the locking mechanism includes a first working position and a second working position; in the first working position, the hooking groove faces and cooperates with the locking groove to lock a locking rod of a car seat; in the second working position, the hooking groove is located above the locking groove to form an opening through which the locking rod of the car seat can be released; and wherein the rotating shaft is located at the rear and lower portion of the locking hook. The locking mechanism further comprises: a driving sliding block slidably provided on the base along the length direction of the base; and a first elastic member provided between the base and the driving sliding block so that the locking mechanism can be stably maintained at the first working position, the driving sliding block is connected to the upper portion of the hooking groove above the rotating shaft, wherein the locking hook is provided with a pin, and a front part of the driving sliding block is provided with an aperture into which the pin is inserted. The locking hook has a sheet-like shape and is provided in two sheets provided at an inner side of the driving sliding block respectively. Both sides of the base are provided with arcuate apertures respectively. One pin is provided on the two sheets, and the two ends of the pin are inserted into the arcuate apertures respectively. The locking mechanism further comprises a traction member slidably provided on the base along the length direction of the base, a front end of the traction member connected to the driving sliding block.